Prefix Aggregator

A command-line tool for efficiently aggregating IPv4 prefixes into the smallest possible set of CIDR blocks.

Features

• Aggregates adjacent and overlapping IPv4 CIDR blocks
• Optimizes for the smallest number of resulting prefixes
• Works with standard input/output for easy integration with other tools
• Cross-platform support (Linux, macOS, Windows)

Installation

Download Binary

Pre-built binaries are available for various platforms on the Releases page.

1. Download the appropriate binary for your platform:

   • Linux: prefix-aggregator-x86_64-unknown-linux-gnu.zip
   • Windows: prefix-aggregator-x86_64-pc-windows-gnu.zip
   • macOS (Intel): prefix-aggregator-x86_64-apple-darwin.zip
   • macOS (Apple Silicon): prefix-aggregator-aarch64-apple-darwin.zip

2. Extract the ZIP file and place the binary in a directory included in your PATH.

macOS Security Warning

When running the application on macOS, you might see a security warning: "Apple could not verify this app is free from malware."

To resolve this:

1. Right-click (or Control-click) on the prefix-aggregator binary
2. Select "Open" from the context menu
3. Click "Open" in the dialog that appears
4. The app will now be saved as an exception to your security settings

Building from Source

If you have Rust installed, you can build from source:

git clone https://github.com/ugwis/prefix-aggregator.git
cd prefix-aggregator
cargo build --release

The binary will be available at target/release/prefix-aggregator.

Usage

Basic Usage

Provide a list of IP prefixes via standard input:

prefix-aggregator < list_of_prefixes.txt

Or use a here document:

prefix-aggregator << EOF
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
EOF

Examples

Example 1: Aggregate Adjacent Prefixes

Input:

10.0.0.0/24
10.0.1.0/24
10.0.2.0/24

Output:

10.0.0.0/23
10.0.2.0/24

The tool automatically combines 10.0.0.0/24 and 10.0.1.0/24 into 10.0.0.0/23.

Example 2: Handle Overlapping Prefixes

Input:

10.0.0.0/8
10.0.0.0/16
10.0.1.0/16

Output:

10.0.0.0/8

The tool recognizes that 10.0.0.0/8 already includes the other prefixes.

Example 3: Real-world Application

Aggregating AWS IP ranges:

curl -s https://ip-ranges.amazonaws.com/ip-ranges.json | jq -r '.prefixes[].ip_prefix' | sort -V | uniq | wc -l
# 4314 prefixes before aggregation

curl -s https://ip-ranges.amazonaws.com/ip-ranges.json | jq -r '.prefixes[].ip_prefix' | sort -V | uniq | prefix-aggregator | wc -l
# 1101 prefixes after aggregation

This example shows how the tool can reduce 4314 AWS IP prefixes to just 1101 prefixes.

How It Works

The prefix-aggregator uses an algorithm that:

1. Sorts the input prefixes
2. Identifies adjacent prefixes that can be combined
3. Merges overlapping prefixes
4. Recursively applies these operations until no further aggregation is possible

License

MIT License